Since electric and electronic devices have been reduced in size and highly integrated, heat generation of mounting components and a temperature increase of use environment become significant. Therefore, there is an increasing demand for the improvement of a heat radiation property of a component. Currently, metals and ceramics having high heat conductivity are used especially for heat radiating members of car members and high-power LEDs.
General-purpose resin, metal (such as aluminum) having high thermal conductivity, and the like have been used for conventional car LED lamp heat sinks. However, since the general-purpose resin is low in thermal conductivity, there is a problem that the general-purpose resin cannot adequately cool an LED module. Further, the metal such as aluminum is high in specific gravity and requires a post-processing step for improving the heat radiation property. In addition, since production is performed by die casting, there are problems that the degree of freedom in shape is low, the manufacturing cost is high, the durability of a die is low, and the like. Therefore, there is a demand for a resin material which is high in thermal conductivity, is light in weight, has excellent moldability, and can be produced at low cost.
Disclosed as a method of giving the thermal conductivity to resin is a method of adding a highly thermally conductive filler, such as graphite, to the resin.
PTL 1 discloses a resin composition having excellent thermal conductivity by adding specific graphite particles to resin.
PTL 2 discloses an electrically conductive resin composition containing thermoplastic resin and graphite powder in which an aspect ratio of 70% or more of particles of the graphite powder is three or less.
PTL 3 discloses an LED lamp heat sink formed by combining thermally conductive resin and metal having high heat conductivity. However, according to this technology, a filler needs to be highly filled for giving the thermal conductivity, so that there are problems that flowability extremely deteriorates, and molding may become difficult.